This invention relates to a process for hydrogen treating hydrocarbon feeds containing high levels of nitrogen compounds.
Decreasing supplies of high quality petroleum crude oils have focused considerable attention on production and upgrading of lower quality petroleum crude oils as well as synthetic materials. Oil shale shows promise as an abundant as well as reliable source of hydrocarbons that can be converted to products of the type commonly obtained from petroleum hydrocarbons. Unfortunately, typical shale oils contain extremely high levels of nitrogen as well as significant amounts of oxygen as compared to typical petroleum crude oils. Accordingly, to facilitate conversion of shale oils and similar high nitrogen content feed materials to useful products or products suitable for use as feed materials in conventional petroleum refining operations, treatment is required to remove nitrogen.
Of course, nitrogen-containing petroleum crude oils also are known and a number of processes for removal of nitrogen from nitrogen-containing feeds obtained from both petroleum and synthetic crude oils have been proposed. Among these are various solvent denitrification processes which involve extraction of a feed with acids or polar solvents to remove nitrogen-containing molecules, as well as catalytic processes typically involving contacting a feed with hydrogen in the presence of hydrodenitrogenation catalysts whereby nitrogen and hydrogen react to form easily removable nitrogen compounds such as ammonia without substantial destruction or removal of hydrocarbon feed components with which the nitrogen was associated.
Typical catalysts employed in catalytic hydrodenitrogenation processes contain a hydrogenating metal component such as an oxide or sulfide of a Group VlB and/or VIII metal deposed on a refractory inorganic oxide support such as alumina. It also is known that the activity of such catalysts for hydrodenitrogenation reactions can be promoted by inclusion of a phosphorus component in the hydrogenating component as disclosed in U.S. Pat. No. 3,446,730 (Kerns et al.) and U.S. Pat. No. 3,749,664 (Mickelson). Use of catalysts such as those of Kerns et al. or Mickelson in hydrodenitrogenation of high nitrogen content feeds can result in reduction of product nitrogen levels to the point that it is possible to hydrocrack the product in the presence of conventional hydrocracking catalysts. Without a prior hydrodenitrogenation treatment, however, the high nitrogen content of the feed typically poisons conventional hydrocracking catalysts.
In copending, commonly assigned application Ser. No. 200,536 of Tait et al. filed Oct. 24, 1980, an improved catalyst and process for hydrogen processing hydrocarbon feeds, particularly those of high nitrogen content, are disclosed and claimed. The process of that application involves contacting feed with hydrogen in the presence of a catalyst of improved thermal stability comprising a hydrogenating component comprising a chromium component, a molybdenum component and at least one Group VIII metal component and a support component comprising a porous, refractory inorganic oxide component and a crystalline molecular sieve zeolite component. Commonly assigned, copending application Ser. No. 231,757 of Miller, filed Feb. 5, 1981, discloses and claims improved hydrotreating catalysts comprising a hydrogenating component comprising a chromium component, at least one other Group VIB metal component, at least one Group VIII metal component and a phosphorus component deposed on a porous refractory inorganic oxide support. Particularly good results are attained in denitrogenation of high nitrogen feeds.
In copending, commonly assigned application Ser. No. 320,866 filed concurrently herewith, Hensley et al. disclose and claim improved catalytic compositions having utility in a wide range of hydrocarbon conversion reactions comprising an active metallic component comprising at least one metal having hydrocarbon conversion activity and at least one oxygenated phosphorus component and a support component comprising at least one non-zeolitic, porous refractory inorganic oxide matrix component and at least one crystalline molecular sieve zeolite component.
We have now found that certain catalytic compositions according to the aforesaid Hensley et al. application give particularly good results in hydrogen processing of high nitrogen feeds. Accordingly, it is an object of this invention to provide an improved process for hydrogen treating of high nitrogen content hydrocarbon feeds. A further object is to provide a process for denitrogenation hydrotreating and/or hydrocracking of such feeds in the presence of the aforesaid catalysts. Other objects of the invention will be apparent to persons skilled in the art from the following description and the appended claims.
As compared to the phosphorus-promoted, zeolite-free catalysts of the aforesaid Kerns et al. and Mickelson patents, use of the catalysts of Hensley et al. according to this invention yields significantly improved results in terms of both hydrodenitrogenation and hydrocracking. As compared to the above-described hydrogen processing processes employing zeolite or phosphorus-containing catalysts in which the hydrogenating metals comprise chromium, molybdenum or tungsten, and at least one Group VIII metal components, the process of the present invention yields improved results in that improved hydrodenitrogenation and/or hydrocracking can be attained under conditions comparable to those employed according to the aforesaid processes while results comparable to those achieved according to such processes can be attained under less severe conditions according to the present invention.